This invention relates to a discriminating apparatus capable of discriminating genuineness of various certified papers including, for example, bank notes, securities such as stocks and various other certified documents such as slips.
There have been conventionally known discriminating apparatuses for discriminating genuineness of bank notes, securities or like certified papers. Such discriminating apparatuses discriminate genuineness of certified paper by photoelectrically scanning characters, figures, symbols, or (hereinafter referred to collectively as “patterns”) printed in specified positions of the paper, and comparing a scanned pattern with a pre-stored pattern of the genuine certified paper.
However, improved forging technology has made it difficult to discriminate forged certified paper from genuine certified paper only based on usual printed patterns. German Unexamined Patent Publication DE 197 085 43 A1 discloses printing of bank notes with a luminescent ink containing electroluminescent material which emits a light upon application of ultraviolet rays or an alternating voltage. The use of such an electroluminescent ink makes the certified paper luminous upon projection of ultraviolet rays or upon being placed in an alternating-current electromagnetic field and accordingly enables discrimination of genuineness of a certified paper by detecting the presence or absence of the luminous light even if the printed patterns made on the genuine and counterfeit certified papers by usual printing coincides with that of the genuine.
In addition, a system of detecting a light emitted from the certified paper resulting from a corona discharge caused by placing the certified paper in an environment of a high-voltage alternating-current electromagnetic field and discriminating genuineness by comparing a pattern of the detected light emission with a light emission pattern of a genuine certified paper may be added to the above system of optically scanning the printed patterns.
A discriminating apparatus adopting such a composite system can discriminate genuineness not only based on the light emission from the certified paper caused by the corona discharge, but also based on the printed patterns, i.e. the certified paper is doubly checked. Therefore, such a discriminating apparatus is expected to make a highly accurate genuineness discrimination.
In the above composite system, the certified paper is transported to an environment of a high-voltage alternating-current electromagnetic field set in advance, and a light emitted from and a light reflected by a portion of the certified paper having reached a light collecting spot are detected by a light detecting element. However, with such an arrangement, the certified paper is exposed to the environment of the high-voltage alternating-current electromagnetic field while passing a sensor for the discrimination, which presents a problem of deteriorating the certified paper.
In view of the above problem, an object of the present invention is to provide a certified paper discriminating apparatus which adopts a composite discriminating system of discriminating genuineness by detecting a reflected light from and a light emitted from a certified paper being discriminated and is capable of effectively suppressing deterioration of the certified paper.
The present invention is directed to a certified paper discriminating apparatus for discriminating genuineness of a certified paper printed using a fluorescent ink which emits a light upon being placed in an environment of an alternating-current electromagnetic field and emits a fluorescent light upon being illuminated by a light having a specified wavelength, comprising an alternating voltage applying means for applying an alternating voltage to specified electrodes opposed to each other for generating the environment of the alternating-current electromagnetic field; a light detecting means for detecting a light from a light collecting spot of the certified paper being transported in the environment of the alternating-current electromagnetic field; a light emitting means for emitting the light having the specified wavelength toward the light collecting spot; an optically splitting means for splitting the light detected by the light detecting means into a light from the fluorescent ink and an other light; an alternating voltage control means for controlling driving of the alternating voltage applying means; and a genuineness discriminating means for discriminating the genuineness of the certified paper based on an output value of the light detecting means, wherein the alternating voltage control means drives the alternating voltage applying means only when the light detecting means detects the light from the fluorescent ink.
With the apparatus thus constructed, the light detecting means detects the reflected light from the certified paper having its wavelength distribution optically split by transporting the certified paper toward the light collecting spot with the light emitted toward the light collecting spot from the light emitting means. The optically splitting means has such a wavelength selecting property that the light emitting means detects the light from the fluorescent ink based on a difference in wavelength distribution. The alternating voltage control means outputs a control signal to the alternating voltage applying means only upon confirming the light from the fluorescent ink based on a detection signal from the light detecting means, thereby setting the environment of the alternating-current electromagnetic field at the light collecting spot.
Accordingly, the fluorescent ink on the certified paper located at the light collecting spot emits a light, which is detected by the light detecting means. The genuineness discriminating means discriminates the genuineness of the certified paper based on the output value of the light detecting means.
Since the alternating voltage is applied to the certified paper only when the fluorescent ink is located at the light collecting spot, a period during which the certified paper is exposed to the high-voltage alternating-current electromagnetic field is shortened as compared to a case where it is transported with the environment of the high-voltage alternating-current electromagnetic field set at the light collecting spot P from the beginning on. This minimizes an influence on the quality of the certified paper caused by a long exposure time, thereby avoiding undesirable situations where deterioration of the certified paper is advanced by the genuineness discrimination and a lifetime of an insulating element is shortened.
Preferably, the genuineness discriminating means discriminates genuineness based on the output values of the light detecting means representing the light emitted from the light emitting means and reflected at the light connecting spot and the light emitted from the fluorescent ink.
With this construction, the fluorescent ink on the certified paper emits a light at the light collecting spot set in the environment of the alternating-current electromagnetic field, and this light is detected by the light detecting means, whose corresponding output value is sent to the genuineness discriminating means. Further, the light (fluorescent light) emitted from the light emitting means and reflected at the light collecting means is also detected by the light detecting means, whose corresponding output value is sent to the genuineness discriminating means. Since the genuineness discriminating means discriminates the genuineness of the certified paper based on these two output values, precision of the genuineness discrimination can be improved.